noexec on /dev/shm

[Lennart Poettering]

On Mon, 20.12.10 13:07, Fernando Lopez-Lezcano (nando at ccrma.Stanford.EDU) wrote:

> Jack (the Jack Audio Connection Kit, jackaudio.org) has been using the 
> file api (apologies if my wording is not absolutely correct in unix 
> terms) on the tmpfs filesystem that is mounted on /dev/shm for a very 
> long time (10 years?). "/tmp" is not useful to Jack because Jack's 
> internal communication pipes can't be stored in any disk based journaled 
> filesystem as the latencies involved in accessing them cause glitches in 
> the audio streams handled by Jack.

to be frank I don't really buy this. A FIFO or socket in /tmp should be
fine as long as it is opened with O_NOATIME. The data in the fifo buffers
or the socket buffers never ever touches the disk and hence it is
irrelevant whether it is tmpfs or a real disk.

> I raise this issue because "The API for /dev/shm is shm_open()" 
> statement above means to me that in the future there will be no file api 
> access to a ram mounted filesystem in Fedora (I understand that this is 
> my own conclusion, but I can't see any other given the wording of the 
> statement above). Before someone implements that idea, please consider 
> the needs of a filesystem in ram for such uses as those mentioned in 
> this thread (and that is supported by the Fedora distribution by 
> default). Just in case...

This too appears to be a good usecase for XDG_RUNTIME_DIR btw.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.